What is Syngas?

Syngas is the gas produced from the gasification process. Syngas (also know as synthetic gas) can vary in the percent constituents depending on the gasification technology and operating conditions that produced the gas. The table below shows some of the main components that makeup syngas when derived from coal.

As you can see from the table below, syngas is created by partially oxidizing the coal. Otherwords it is not given enough oxygen to reach full combustion. If full combustion is reached, the hydrogen and CO are consumed in the process. 
  
Constituents of Coal                        Gasification                  Combustion
Carbon                                                       CO                                 CO2
Hydrogen                                                   H2                                  H2O
Nitrogen                                                     N2                                  NOX
Sulfur                                                         H2S                                SO2
Oxygen                                                         -                                      O2

The base components extracted from the coal in the gasification process (called syngas) are the building blocks for chemical processes used to produce products listed below.

Chemicals and Fertilizers

Modern gasification has been used in the chemical industry since the 1950s. Typically, the chemical industry uses gasification to produce methanol as well as chemicals, such as ammonia and urea, which form the foundation of nitrogen-based fertilizers. The majority of the operating gasification plants worldwide produce chemicals and fertilizers. And, as natural gas and oil prices continue to increase, the chemical industry is developing additional coal gasification plants to generate these basic chemical building blocks.

Power Generation with Gasification

Coal can be used as a feedstock to produce electricity via gasification, commonly referred to as Integrated Gasification Combined Cycle (IGCC). This particular coal-to-power technology allows the continued use of coal without the high level of air emissions associated with conventional coal-burning technologies. In gasification power plants, the pollutants in the syngas are removed before the syngas is combusted in the turbines. In contrast, conventional coal combustion technologies capture the pollutants after combustion, which requires cleaning a much larger volume of the exhaust gas. This increases costs, reduces reliability, and generates large volumes of sulfur-laden wastes that must be disposed of in landfills or lagoons.

Today, there are 15 gasification-based power plants operating successfully around the world. There are three such plants operating in the United States. Plants in Terre Haute, Indiana and Tampa, Florida provide baseload electric power, and the third, in Delaware City, Delaware provides electricity to a Valero refinery.

Substitute Natural Gas

Gasification can also be used to create substitute natural gas (SNG) from coal and other feedstocks, supplementing U.S. natural gas reserves. Using a "methanation" reaction, the coal-based syngas—chiefly carbon monoxide (CO) and hydrogen (H2)—can be profitably converted to methane (CH4). Nearly identical to conventional natural gas, the resulting SNG can be shipped in the U.S. natural gas pipeline system and used to generate electricity, produce chemicals/fertilizers, or heat homes and businesses. SNG will enhance domestic fuel security by displacing imported natural gas that is generally supplied in the form of Liquefied Natural Gas (LNG).

Hydrogen for Oil Refining

Hydrogen, one of the two major components of syngas, is used in the oil refining industry to strip impurities from gasoline, diesel fuel, and jet fuel, thereby producing the clean fuels required by state and federal clean air regulations. Hydrogen is also used to upgrade heavy crude oil. Historically, refineries have utilized natural gas to produce this hydrogen. Now, with the increasing price of natural gas, refineries are looking to alternative feedstocks to produce the needed hydrogen. Refineries can gasify low-value residuals, such as petroleum coke, asphalts, tars, and some oily wastes from the refining process, to generate both the required hydrogen and the power and steam needed to run the refinery.

Transportation Fuels

Gasification can be used to produce transportation fuels from oil sands, coal and biomass.

The Future of Gasification

Worldwide gasification capacity is projected to grow 70 percent by 2015, with 80 percent of the growth occurring in Asia. The prime movers behind this expected growth are the chemical, fertilizer, and coal-to-liquids industries in China, oil sands in Canada, polygeneration (hydrogen and power or chemicals) and substitute natural gas in the United States, and refining in Europe.

The use of gasification is expanding. Several gasification projects are under development to provide steam and hydrogen to upgrade synthetic crude in the oil sands industry in Canada. In addition, the paper industry is exploring how gasification can be used to make their operations more efficient and reduce waste streams.
A number of factors contribute to a growing interest in gasification, including volatile oil and natural gas prices, more stringent environmental regulations, and a growing consensus that CO2 management will likely be required in power generation and energy production.

China is expected to achieve the most rapid growth in gasification worldwide. Since 2004, 29 new gasification plants have been licensed and/or built in China. In contrast, no new gasification plants have begun operation in the United States since 2002.

Bioprocessing

In addition to using the traditional feedstocks of coal and petroleum coke,gasifiers can utilize biomass, such as yard and crop waste, “energy crops”, such as switch grass, and waste and residual pulp/paper plant materials as feed. Municipalities as well as the paper and agricultural industries are looking for ways to reduce the disposal costs associated with these wastes and for technologies to produce electricity and other valuable products from these waste materials. While still in its infancy, biomass gasification shows a great deal of promise.

A Link to the Future

Gasification is a “link” technology to a hydrogen economy. Because gasification converts feedstocks such as coal directly into hydrogen, it can become a competitive route to producing the large quantifies of hydrogen that will be needed for fuel cells and cleaner fuels. By contrast, other technologies must first create the electricity needed to separate the hydrogen from water, using